Worm gear drive



Dec. 1, 1959 E. w. @LEM 2,914Q864 WORM GEAR DRIVE Filed Jan. 24. 1956 3 Sheets-Sheet 1 Everer'' W. Clem l if@ mv@ ATTORNEYS D. 1, 1959 E. w. cLEM 2,914,864

` WORM GEAR DRIVE 4 Filed Jan. 24, 1956 3 Sheets-Sheet l2 INVENTOR Everett W. Clem ATTORNEYS Dec. 1, 1959 E. W.V CLEM 2,914,864

woRM GEAR DRIVE Filed Jan. 24. 195s s sheets-sheet s INVENTOR BYEvere'n` W. Clem l )WM-lf ATTORNEYS 2,914,864 f lWORM GEAR DRIVE Everettw. Clem, I Shrewsbury, Mass., assgnor to Rice yBarton Corporation, Worcester, Mass., a corporation of Massachusetts n application January 24, 1956, serial No.' 561,004

1s claims. (cl. 34-121) `",fhvisginvention relates to worm gear drives` for hot journal applications andmore particularly to such a drivej'in" which the operating members will properly co- ,act with one anotherthmroughout a wide range of operating temperatures.V More especially the invention is concern'ed with aworm gear drive lparticularly useful for driving the drying rolls of drums of Va paper machine bringing it-up`tolspeed andfrom slowing it down and nally vstoppingzit,` issubstantial. Backlash, which has acumulativo effect on such Wear, can and will result.

Afurther important disadvantage and limitation of directgeantraindrives is encountered when, in an effort to obtain agreater exposureof the web being dried so that the moisturetherein Willhave a greater opportunity `to leave, the drying rolls :are spreadfarther apart. This is, ofcourse, because -when therolls are spread farther apart larger gears must belemployed and as a result the 2 a lworm 'gear drive whichwill be satisfactorilyoperable and` substantially freefrom backlash over a wide range of operating temperatures. It is a further object of the invention, to ,provide such a drive which permits operation at increased speeds and at greater rolll spacings than heretofore possible. The invention ntherefore contemplates the provision of an individual drive forveach drying roll of la drying section fora paper vmachine whereby backlashoccurringin vone drive isfsubstantially conned theretoand has no effecty whatever on any ,other drive and whereby the gears may be maintained small enough so that at the higher speeds of `operation, the linear velocities of the gear teeth karevvell ybelow the `safe maxi.- mums. j n K Hence'my invention advantageously contemplates the provision, in a worm gear, drive for hot journal applications, iof a worm, a worm gearv .mounted 'thereabove uponr the ,shaft of an object` to be driven, and a bearing supportingthe shaft, the axis Vof the worm and the axis of the bearing (axis ,of outerrace) being spaced apart Va greater distance than the sum Vof the pitch radii ofthe Worm and the worm gear for reasons that will hereinafter be fully explained. Also contemplated by myhinventio'n isthe provision of a bearing support of such. construction as to permit removal of thewormH gearfrom the shaft Without removal of the'bearingV and the provision `ofa worm support accommodatingreadyremoval of the worm vand its supporting shaft for purpose hereinafter noted. In addition, my invention,contemplates,the` employment of an anti-frictionbearing, advantageously a spherical roller bearing, and includes a Wormlgear the teethof which are so hobbed vas to permit satisfactory meshing with the worm despite'shift of the Worm gear linearvelocity of the open gear teeth sincreased and `may.approach'or even exceed thesafe maximum. In

such cases, lgear life` is quite naturally radically reduced. Various diierent drive mechanisms have therefore `been. proposed and employed in the past in an effort to minimize the effect ofbacklash to permit greater drying roll separation and to accommodate out-of-balance etc.,

,some involving the interposition and use of .smaller `chain! stretch and the normal limitations of belt drives .haveprevented their being entirely satisfactory. vStill othersV` haveemployed. worm gear drives whereby each 'roll is individually driven through a worm gear or a seriesfof spur-'gears Afrom-asingle worm shaft forthe rolls ofone tier of the dryer section. Thelast-mentioned approach was hindered, however, byvdiiiculties encountered vby reason of the fact `that the drive mechavnisms,4 forpaper machine drying sections must be operable over awide variation of temperature conditions. This results from the fact that hightemperature steam for heating the drying rolls may have to be supplied thereto through their supporting shafts upon which are also supported the driving gears. Hence the driving Vmechanisms and journalsfor supporting and driving the rolls may be subjected to substantial heat.

'm'lt is` the primary object-of this'invention to provide I axially as a result of a shifting of the inner race of the bearing in response to the ridingn of the spherical rollers up the outer race in either direction because of a lchange in thrust imposed axially under changing loading conditions such las will be experienced in acceleration and deceleration in the speed of rotation of the driven object. Furthermore, the drive of my invention contemplates adjustment means for adjusting theposition of the worm gear axially with respect to the worml to obtain the optimum relative positioning thereof under aV particular running condition. Also my invention contemplates` provision for ready removal of the support bearing. For a more detailed understanding of thefinv'ention, reference may be made to the following description of one embodiment thereof employed specifically inthe drive of the dryer rolls of afpaper' machine `dryer lsection. This specific description will be given inv connection with the accompanying drawings inwhich: i

Eig. 1 is a sidegelevation of a" paper machine drying section provided with my' novel worm"`gea.r"drive;,` i Fig. 2 isa sectional'view inelevationo'f'one ofthe worm gear drives employed; and v Figs. 3 and 4 are sectional views takenrespectively along lines 3-3and 4--4 of Fig-'2'.` f 1 Referring irst to Fig.l `of, the drawings, therefisfillustrated a paper machine drying'section made up` generally of a supporting framework f10.for. supporting a plurality of drying rolls or drums 11 in twol tiers and afelt framework'10. Each of the driving rolls 111'is` supported at one endin a journal housing,indicatedgenerallyv by.` the reference numeral 12. Each housing-12 also `enclosesa portion of 'a worm gear drive, the remainder` of' whichis enclosed within a worm housiugyl.A The individual worm drives are interconnected by connectingV shafts 14 carrying at their opposite ends semi-flexible couplings 15 by which they are connected tothe rworm shafts `16. Driving power for shafts 14 and the Worm `shaftsl isfsupplied to the dryer section through a main `driveshaft 18 to which is secured la bevel gear`119 `meshing 4yvitha,heuvel gear on one of the connecting shafts 14 of the lower flight. This connecting shaft 14, which may be termed the intake shaft, supports at its opposite ends fully llexible couplings 22 by which it is secured to the worm shaftsof the two adjacent dryer rolls. lThis intake connecting shaft 14 also supports a second bevel gear 23 within housing 24 which meshes with a bevel gear 25 supported at the lower end of av drive connecting sh-aft 26 to the upper end of which is secured a further bevel gear 27 which meshes with a like bevel gear 28 within worm housing 13 located above the intake connecting shaft 14. Bevel gear 28 is secured to the worm shaft 16 extending through said upper worm housing and hence provides the intake for the drives of the upper tier of dryer rolls. The dryer section illustrated in Fig. 1, it should be understood, is not complete in detail in that numerous doctor blades, guide rolls, etc., are not illustrated.

In Figs. 2 through 4, one ofthe individual drives for a dryer roll 11 having a supporting shaft 30 is illustrated in greater detail. The journal housing 12 and worm housing 13, as illustrated, are formed in part from a two-part casting (Fig. 3) having an opening 31 through the rear end thereof to receive shaft 30. This opening 31 in the housing is provided with a channel 32 surrounding a groove 33 in the surface of the shaft 30 which cooperate to trap any oil tending to escape from the housing through opening 31 and return it thereto through bore 32. A worm gear support member 35 surrounds a forward portion of shaft of reduced diameter and is tightly secured thereto by a plurality of bolts 36 (Figs. 2 and 3). Two drilled holes 36' tapped at their ends adjacent the shoulder on shaft 30 are provided to accommodate jacking of supporting member for removal thereof from the shaft. Worm gear support 35 is also provided with a flange 37 provided with a plurality of axially extending bolt holes adapted to correspond in location and number to those of a worm gear 38 which may be secured thereby to support member v35 by a plurality of bolts 39. Complementary keyways 30' and 35' are forced in shaft 30 and worm gear support member 35 respectively,v a torque carrying key K being located therein for transmitting driving force from the latter to the former. Y

While keyway 30' is of limited length, as shown in Fig. 2, and is adapted to have the key dropped into it and to hold the key in place, keyway 35 extends throughout the length of member 35 thereby permitting it to be slid onto the shaft over the key. Worm gear 38 is adapted to be drivingly engaged by a worm 40 mounted on worm shaft 16 which traverses the lower portion of the composite worm-worm gear housing.

As best illustrated in Fig. 3, the opposite ends of the worm shaft 16 are keywayed for ready reception in a coupling, such as shown at 15, in Fig. l. Worm shaft 16 is supported on ball bearings at one end thereof located within an opening in the worm housing and maintained therein by a capping member or cover 51 secured by bolts 52 to the housing and surrounding the end of shaft 16.

`Ball bearings 50 surround a reduced portion of shaft 16 and are shrunk fit thereon, one abutting the shoulder so formed. The opposite end of worm shaft 16 is supported in a ball bearing 54 also shrunk f1t thereon and abutting a .shoulder thereon through a spacer 55. A spring 56 is interposed between the ball bearing 54 and a packing 64 and urges the latter into sealing relation with an inner face of a cap or cover 57 surrounding this end of worm shaft 16 and again secured to the worm housing by suitable bolts or tap screws 58. In this instance ball bearing 54 is located within an inwardly extending flange 60 of cap or cover member 57. A similar spring 62 surrounds the end of worm shaft 16 within cap member 51 and is compressed between a pair of collars 63 threadedly mounted on this end of shaft 16 and a packing 64 to urge the latter into sealing relation with the inner face of cap member 51. Packings 64 prevent the escape 4 of lubricant through the openings in cap members 51 and 57.

Removal of the worm and its supporting shaft may, as will be clear from the above, therefore be simply accomplished merely by removal of the cap members and turning of worm and shaft to thread the former past worm gear 38, openings 65.(Fig. 3)l in the worm housing being large enough to passthe worm. This feature is of considerable importance Vforvthe reason pointed out below.

Taps 68 and 69 (Fig. 2) `are provided through the worm housing wall to accommodate the drainage of the vlubricant therefrom and cleaning of the interiori thereof respectively. n y j Shaft 30 forwardly of the worm gear supporting section is provided with a tapered section 70 adapted to receive or be received by a spherical roller bearing 71 having inner and outer races 72 and 73 respectively, between which are contained spherical rollers 74. The inner race 72 of the bearing is maintained on the tapered section 70 of shaft 30 by a retaining collar 75 adapted to be threaded on shaft 30. A lock washer 76 is interposed between collar and the roller bearing.

The outer race of the bearing is supported by a twopart (Fig. 4) bearing supporting member 78 adapted to surround it within the forward portion of the composite housing 12-13. Bearing supporting member 78 is provided with an inwardly depending ange 80 at its inner end adapted to engage the rear face of outer race 73 of roller bearing 71. The purpose of this ange 80 will be subsequently explained.

A plurality of adjusting screws 83, only one of which may be seen in Fig. 2, but three in number, as may be seen in Fig. l, for each bearing supporting member, two being contained in the lower half of the bearing supporting member and the third, which is that illustrated in Fig. 2, being contained in the upper half thereof, extend through the peripheral forward flange 84 of the composite bearing supporting member 78. These adjusting screws 83, as illustrated in Fig. 2, are adapted to engage the forward rim of the composite journalhousing 12-13. A plurality of positioning bolts or tap screws 85 (Fig. 2) also pierce flange 84 of the bearing supporting member and are adapted to be threaded into the composite journal housing to secure the bearing supporting member in any adjusted position therein. A one-piece cap member adapted to surround the outer end of the shaft and close the bearing exposing opening in the outer face of bearing supporting member 78 is provided and is secured to the bearing supporting member lby a plurality of bolts or cap screws 91.

Dryer roll shaft 30 is hollow, being provided with an axially extending bore therethrough through which a heating medium may be supplied to the interior of dryer roll 11. For this purpose the extreme outer end of shaft 30 is so designed as to receive a steam joint adapter.

There are two features of primary importance in the illustrated construction, the rst of which is that the worm 40 is located below the driven worm gear 38. 'I'he second feature is that the construction is so designed that the center line of the bearing, that is, the center line of the outer race, which center line is labeled B (Fig. 2) is above the center line S of shaft 30, the center line B of the bearing being the center line of the outer race 73 thereof. Hence, as heretofore mentioned, the axis B of the bearing is spaced from the axis W of the worm a distance greater than the sum of the pitch radii of worm 40 and worm gear 38, the axis of worm gear 38 coinciding with the axis S of shaft 30.

The importance of these two features is as follows. Under normal conditions, due to the weight of dryer roll 11 which is substantial, the inner race of the bearing is positioned downwardly olf-center from the outer race, leaving the clearance that has exaggeratedly been shown as clearance C in Fig. 2. This means that were lthe center line .Blof thel'bearing tocoincide with the center line S of thelshaft and worm gear 38 as it would be were the design purely theoretical, under normal cold operation (roorn temperature) worm gear 38 and worm 40 would mesh tightly. With the `indicated construction, howwel',v the` shift downwardly of the inner race of the bearing'isl. such that .the axisA of the worm gear is properly .fspacedfrom the axisk of the Worm for cold operation. As

`the shafgand itsrsuppor'tedparts and the bearing 71 heat up .id uring operation of the dryer, worm gear 3 8 expands, which would 'normally result in too tight a mesh between Iit and worm `gear 40. However, at thesam'e time bearing 71 expands, thus "raising shaft 30 'and hence worm gear 38 awayfromworrn 40. v A bearing71 is therefore chosen havinganf'internal clearance and an expansion characteristie such'tha't when it expands it raises the Worm gear and 'its E'supporting part to cancel out substantially the expansion of the worm gear, therebytendin'g to maintain the mesh of it and .the worm 40 constant. While standard bearingst are not available with infinitely different amounts f clearance or .expansion characteristics, .the character- 4ilsticsfof `a standard bearing employed in the illustrated eons'trction may be'modied by the axial positioning of the bearing on tapereds'ection 70` of shaft '30. This posifti'oV rig 'mayf be 'accomplished by employing collar 75 to urg .thejbearingonto 'the shaft beyond the position to which itfnray 'be' urged by hand pressure alone. v

2I-I'en'cein the illustrated construction, a proper uniform meshingofworxn gear 38 and worm '40 may be main- `tainedfboth'infcold operation as well as in hot operation. "It Willbe clearthat were `the wormto be located above fthe worm gear, either/the cumulative expansions of the "gear and its supporting parts and ofthe bearing might prevent 'optimum meshing under hot operating conditions or' require a design which would not optimum meshing under'fcold'operation.

' Propertmeshing of wo'rrny gear v'8 and worm 40 also -invlves prperpositioning of the two relative-to each other Vin a direction "axially ofthe 'worm gear. The rela- "tivepositionlinthis direction isalso affected by change .i`n` temperature 'as `well'a's by thrust forces imposed during #operation "To permit adjustment for optimum meshing yin-this respect, provision is made'for movingy shaft 3u and 'hence worm gear 38 axially. `Hence bearing 71, which "ali'here'tdfore:described is tightly held onto the shaft by collar 15,"may .bepunea to the right, as shown lin Fig. 2,

' adjustment-pf worm gear v 38-mayn'ormallyv be done by pection durngiop'eration under given conditions. .Sutthvisuahobs'erva'tionlmay be accomplished by removal hortperiodof observation under the actual 'con- 'are lbe'ingmarked, `a determination gcan ybe made as to `whether or not theworm gear is properly locatedaxially r `rvlithrespecttojthe worm,land ifno't, the lower `two adijustlng screws 83 :set to reposition `it to proper Irelative position. The top hait ef the journal 4is then replaced and :securing bolts 85 tightened. "Because, `as noted, lthe adljustrnent may be made 'during' operation, no compensat- As indicated innig. '2 by the reference letter H, I and it:advantageousto'have asub'stantial Acentral portion-of the'wonngear -teethhobbed -for propermeshing with 'worm 'i140 despite 'temporary relative axial movement of "the A'worm gear with respect to the worm, such for ex- Wampleas `will be encountered in acceleration and deceljf'eration 4of the speed of rotation of the shaft 30. This xialjmovement #results in such instances because of enporti'on of journal housingy 12. \By observing,`v`

the riding up of the spherical rollers 74 of bearing 71 upon the outer race Vin one direction or the other.

` There are additional beneficial features in the illustrated construction. Hence, for example, by reason of this construction worm gear 38 may be removed without removal of bearing 71. This is accomplished by first removing the upper portions ofboth the journal housing 12'and the bearing supporting member 78 as well as end cap 90. The securing bolts for the lower portion of bearing supporting member 78 may then be removed and the lower portion of the bearing supporting member 78 revolved on the bearing, the outer race Aof the latter being free, and the shaft 30 then being supported temporarily by the lower portion of the journal housing surrounding opening 31. Upon a half revolution of movement or thereabouts, the lower portion of the bearing supporting member may be removed in an upward direction. Thereafter worm gear .38 may be vdetached from its supporting member 35 and drawn outwardly overbearing. 71.

By the same partial dismantling `of the journal housing and removal of the bearing supporting member 78, the bearing itself may be removed from shaft 30 without requiring removal of the dryer roll from `the dryer or the shaft thereof completely from the journal.

"By employing a worm of shallow pitch as illustrated, backlash encountered in the operation of the dryer section illustrated and `provided with the worm gear drive of'this'invention may be absorbed in the individual worm gear drive. Furthermore, the stopping torque may be taken up almost entirely in the worm if the pitch thereof is sufficiently shallow. i

Another feature of the construction which should not be overlooked is the 'provision of a Weir T in the lower portion of the gear housing (Fig. 2) which is provided to maintain `a proper level of the lubricant therein for lubrication of the worm, and which will provide a safety reserve of lubricant in the event of a failure of the supply `of lubricant to the gear housing. While this safety reserve will not vpermit extended operation of the drive mechanism without additional lubricant, it will prevent dam-age being done for a short time.

Among the advantages of the above-described worm gear drive in a paper machine dryer section are that it reduces substantially the expense of drive gear maintenance and permits operation of the dryer section at greaterspeeds than have heretofore been possible, the

'contemplated "speeds of operation of the illustrated dryer vbeing as much or'more than 2500 feet per minute.

Furthermore, a paper machine dryer section provided with vthe described worm gear drive is much more open in that the drive side is not closed or substantially closed by gear casings as it would be with a conventional direct gear train drive. kIn such drying apparatus this is.of extreme importance, as good air circulation is depended yupon foi-.uniform drying. This latter feature also permits one a choice ofproviding the heating medium at the front 'or the back side ofthe section. In addition, the fact that the dryer section isv open at both sides permits easier `access to the interior thereof for the removal of broke lremainder of the drying rolls by simply removing the 4worm and its supporting shaft for any drum to be skipped from its gear housing 13 in the manner hereinbefore described, and substituting a drive shaft, similar to drive yshafts I4, therefor.

Still another advantage of the above-described drive mechanism is the fact that it permits limited relative movements or relocations of the dryer rolls with respect to 7 c t oneariothen'as by reason for example of building settling, earthquakes or'other causes for frame-changes. This is s o because the -individual drives made up of a worm, worm gear,'etc., are built in their individual housing and hence are relatively fixed -with respect to one another, the exiblecouplings between shafts 14 and the worm shafts accommodating the changes instead. In open spur gear drives this is not possible and small changes in relative positions of the drying rolls as a result of earth- `quakes, building settlings, etc. may vmake the drives inoperable from a practical point of View.

Various changes and modifications may of course be made in the `apparatus specifically illustrated and described without departing from the scope of this invention which rather should be limited only to the extent setforthin the appended claims.

I claim:

LA worm gear drive for hot journal applications, where the object to be driven is` of substantial weight, comprising a worm, a worm gear mounted on the shaft of the object to be driven, said worm gear being located above said worm and being expandable upon heating, an anti-friction bearing having an outer race and adapted to support the weight of said` shaft and object, and means for supporting the outer race of said anti-friction bearing relative to said Worm'in operation at room temperature so that the axis of the outer race of said anti-friction bearing is spaced from the axis of the worm a distance greater than the sum of the pitch radii of said worm and vsaid worm gear, said worm gear and said anti-friction bearing having matched temperature expansion characteristics, the arrangement being such that the expansions of said anti-friction bearing-and said worm gear upon heating tend to offset one another to maintain said worm and worm gear in proper mesh.

2. A worm gear drive for hot journal application, where they object to be driven is of substantial weight, comprising a worm, a worm gear supporting member fixedly mounted on the shaft of the object to be driven, an annular worm gear adapted to be secured to the outer peripheral part of said worm gear supporting member, said yworm being located below said worm gear, an antifriction bearing for supporting the weight of the shaft and object and having an inner race such that it may be yadjustably positioned on a seat on said shaft and thereby mechanicallyexpanded to a predetermined degree, the diameter of the outer race of said roller bearing being smaller than the inner diameter of said annular Worm gear, means for securing the bearing on said shaft in `adjusted position against axial movement relative thereto, and a multi-piece bearing supporting means for supporting the outer race of said anti-friction bearing relative to the worm so that the axis of the outer race thereof is spaced from the axis of the worm a distance greater than the sum of the pitch radii of said worm and said worm gear, said bearing supporting means being adjustable for movementof the bearing, the shaft and the worm gear axially of the latter relative to the Worm, and said worm gear teeth being hobbed to provide on each a section of substantial axial extent for proper meshing with the worm despite variation in the relative position of the worm and the worm gear axially of the latter.

3. A `worm geardrive according to claim 2 which includes a housing for said worm in which there is an o'il outlet and in which there is also a Weir between the outlet and said worm for maintaining a pool of lubricant within the housingand around at least aV portion of said worm. n A

4. A paper vmachine dryer section comprising Va plurality of drying rolls each supported by a hollow drive shaft through which steam maybe transmitted to the interior thereof, an'individual worm gear drive for each drives, each of said worm gear drives comprising a worm,

.drying .roll andmeans interconnecting lthe Worm gear a worm' `gear supporting member mounted on the shaft oftheadjacent drying'roll, an annular worm gear adapted to be secured to the outer peripheral part of said worm gear supporting member, said worm being located below said worm, gear, a spherical roller bearing having a tapered inner race for adjustable positioning on a tapered seat onsaid shaft, the diameter of the outer race of said roller bearing being smaller than the inner diameter of said annular worm gear, means for securing the bearing on said shaft in adjusted position against axial movement relative thereto, and a multi-piece bearing supporting means for supporting said spherical roller bearing relative to the worm so that during'operation at room tempearture the axis of the outer race thereof is spaced from the axis of the Worm a distance greater than the sum of the pitch radii of said worm and said worm gear, said bearing supporting means being adjustable for movement of the bearing, the Shaft and the worm gear axially 'of the latter relative to the Worm, and said'worm gear teeth being hobbed to provide on each a section of substantial axial extent forv proper meshing with the worm despite variation in the relative position of the worm and the worm gear axially of the latter.

5. A worm gear drive for hot journal application comprising a worm, a worm gear supporting member xedly mounted on the shaft of an object to be driven, and spaced inwardly of the end ofthe shaft, an annular worm gear adapted to be secured tol the outer peripheral part of said worm gear supporting member, an antifriction bearing having an inner race such that it may be adjustably positioned on a seat on said shaft and thereby mechanically expanded to a predetermined degree, said bearing being positioned between said supporting member and the end of s-aid shaft, the diameter of the outer race of said anti-friction bearing being smaller than the inner diameter of said annular worm gear, means for securing the bearing on said shaft in adjusted position .against axial movement relative thereto, and a multipiece bearing supporting means for supporting said antifriction bearing, said bearing supporting means being adjustable for movement of the bearing, theshaft and the worm gear axially of the latter relative to the worm.

6. A paper machine dryer section comprising a plurality of drying rolls each supported by a hollow drive shaft through which steam may be transmitted to the interior thereof, an individual worm gear drive for each drying roll and means interconnecting the worm gear drives, each ofsaid worm gear drives comprising a worm, a worm gear supporting member mounted on'the shaft of the adjacent drying roll, an annular worm gear adapted to begsecured to the vouter peripheral part of said worm gear supporting member, a spherical roller bearing having a tapered inner race for adjustable positioning on a tapered s eat on said shaft, the diameter of the outer race of said roller bearing being smaller than the inner diameter of said annularworm gear, means for securing the bearing on said shaft in adjusted position against axial movement relative thereto, and a multi-piece bearing supporting means forsupportng said spherical roller bearing, said bearing supporting means being adjustable for movement of the bearing, the shaft and the worm gear axially of the latter relative to the worm, and said worm gear teeth being hobbed toprovided on each a section `of substantial axial extent for proper meshing with the worm despite variation in the, relative position of the 'worm and the worm gear axially of the latter.

7. 'Af paper machine dryer section comprising a plurality ofdrying rolls, an individual worm gear drive for each drying roll and means interconnecting the worm .gear drives, each of said worm gear drives comprising a worm, a worm gear mounted on the shaft of the adjacent dryingroll and spaced inwardly of the end of the worm gear and having a portion thereof removable for egsiasezi t 4 1'9 y visalf' access to"said"vvorm"'g`ea1r, an anti-friction bearing mounted on said drying rollshaftoutwardly of the worm gear, `a 4'multi-piece :bearing support` member" mounted-'1n saidgear housing, rneansyforI adjusting" said' bearing sup- `porting member with'respect to said gear housingwhereby removable withoutfdisturbing the position of said bearm'ofuntedon `the shaft of theobjectto beA driven, anl

annulargworm 'gear' adapted to vbev secured tothefjouter priph'eralpart of Asaidvvorm gear `sup`portingmember,

said worm"'beinglocated` below said Worm gear, an anti- `friction bearing having an inner race,jsuch that 1t may be adjustably positioned on a seat on said shaft, ,the inner race of anti-friction bearing being tapered and the seat therefor on said shaft being similarly tapered whereby said inner race. may be mechanically expanded to a predetermined'ndegree, the diameterof the outer race of said roller bearing being smaller than the inner diameter of said 'annular Worm gear, means for securing the bearing on said shaft in adjusted position against axial movement relative thereto, and a multi-piece bearing supporting-means for supporting said anti-friction bearing relative to the Worm so that the axis of the outer race thereof is spaced from the axis of the worm a distance greater than the sum of the pitch radii of said Worm and said worm gear, said bearing supporting means being adjustable for movement of the bearing, the shaft and theA v rworm gear axially of the latter relative to the Worm,

and said Worm gear teeth being hobbed to provide on each a section of substantial axial extent for proper meshing with the Worm despite variation in the relative posi- `tion of thefWorm and the worm gear axially of the latter.

.t 9. A worm gear` drive for yhot journal applications WhereI the object to be driven is of substantial weight, comprising a Worm, a Worm gear mounted on the shaft of the object to be driven, said Worm gear being located above said Worm and being expandable upon heating, an

`anti-friction bearing adapted to support the weight of said shaft and object, said bearing being provided with a tapered inner race for adjustable positioning on a tapered lseat on saidlshaft, means for adjusting said inner race axially on said seat for regulating the expansion characteristics of said bearing, and means for supporting the outer race of said anti-friction bearing rrelative tosaid4 Worm in operation at room temperature so that the axis ofthe outer race of said anti-friction bearing is `spaced from the axis of the worm a ldistance greater than the sum' of ,the pitch radii of said worm and said worm gear, the arrangementbeing such that expanvsions of said `anti-friction bearing and said worm gear upon heating `tend to offset one another to maintain said Worm and Worm gear in proper mesh.

10. A Worm gear drivefor `hot journal applications where the object to be ,driven is of substantial Weight, comprising a worm, a worm gear mounted on the shaft of the object to be driven, said worm gear being located above saidworrn and being expandable upon heating, an anti-friction'bearing having an outer race and adapted to support the Weight of said shaft and object, means for .securing `the bearing, on said shaft against axial movement relative thereto, and means for supporting the outer race of said anti-friction' bearing relative to said worm in operation at room tempertaure so that the axis of the outer race of said anti-frictionv bearing is spaced from the axis of the worm a distance greater than' the sum of f y the pitch radii of said worm andsaid worm gear, said 1`0 bearing "supporting -me'answbeing adjustable for movementv 'ofthe'bearingthe shaft and the worm gear axially ofthe latterrelative to'th'e Worm, the arrangement being such-:that expansions'of f said anti-friction bearing and said Worm'gearupon heatingtend to odset one another n tomaintain saidworm and4 worm gear in proper mesh.

ll. A Wormlgear drive yfor hot journal applications whereftheobject to be `driven is .of substantial weight, comprisinga "Worm, a Worm. gear `mounted on the shaft o'f the objectto be driven, "saidworm gear being located j aboveisaid Worm and beingexpandable upon heating, an

anti-friction bearing having an outer race and adapted to' supportthe Weight of said shaft and object, and means forsupporting the outer raceof `said.fantifriction bearing relative to ,saidWorm in operationatroom temperature-`so that vthe axis of the iouterrace of rsaid 'antifrictiony bearing'` is spaced from the .axis of the worma distance greater rthanthesum of the pitch radii of said Worm vand said Wormv gear; said bearing supporting means `being madefup of at .leasttwo-.pieces wherebyit may be removed other than axially of the shaft, the worm gear being of annular form and having an internal diameter greater than the outer diameter of said bearing, whereby the'worm gear may be removed and replaced without removing said bearing, the arrangement being such that expansions of said anti-friction bearing and said worm gear upon heating tend to offset one another to maintain said Worm and Worm gear in proper mesh.

12,.'A worm gear drive for hot journal applications Where the object to be driven is of substantial Weight,

, comprising a Worm, a Worm gear mounted on the shaft of the object to be driven, said Worm gear being located above said Worm and being expandable upon heating, an annular gear supporting member xed to the shaft, said Vworm gear being annular and adapted to be secured to the outer peripheral portion of the Worm gear supporting member, an anti-friction bearing having an outer race and adapted to support the Weight of said shaft and object, said Worm gear supporting member having an inner diameter greater than the outer diameter of the antifriction bearing, and means for supporting the outer race of said` anti-friction bearing relative to said Worm in operation at roomv temperature so that the axis of the comprising a worm, a worm gear mounted on the shaft of the object to be driven, said Worm gear being loca-ted above said worm and being expandable upon heating, said worm gear teeth being hobbed to provide a section on each of vsubstantial axial extent for proper meshing With the Worm despite limited instantaneous variation in the relative position of the worm and the worm gear axially of the latter, an anti-friction bearing having an outer race and adapted to support the weight of said shaft and object, said anti-friction bearing being a spherical roller bearing, and means for supporting the outer race of said anti-friction bearing relative to said worm in operation at room temperature so that the axis of the j outer race of said anti-friction bearing is spaced from connecting the vWorm gear drives, each of said worm gear drives comprising a worm, a worm gear mounted on the shaft of the adjacent drying roll and above said worm, said shaft being hollow to permit the transmission of a heating medium therethrough to the interior of said drying roll, an anti-friction bearing having an outer race andV mounted on said shaft-for supporting the weight of the shaft and drying roll, andmeans for supporting the outer race of said anti-friction bearing so that its axis isspaced from the axis of the worm a distance greater than the sum of thepitch radii of said Worm 'gear and Worm. v l

15. A papermachine dryer section comprising a, plurality of drying rolls adapted tobe heated, anindividual worm gear drive for each drying roll, said drying rolls being arranged in a plurality of flights the drives of an upper Hight being connected to the drives of a lower ight by a single drive shaft an individual worm shaft being provided for eachworm gear drive, individual shafts connecting each pair of adjacent worm shafts, a 20 exible coupling being mountedon each end of a connecting shaft to ksecurehit tothe end of the adjacent worm shaft,each` of said worm gear drives comprising aV worm', avvorm gearmounted on the shaft of the adjacent-gdrying roll vand above said Worm, an anti-friction bearing having an outer race and mounted on said shaft forfsupporting'the weight of the shaft and drying roll, and; means for supporting the outer race of said'antifriction bearing so that its axis is spaced from the axis ofthe Worm a distance greater than the sum of the pitch radii of said Worm gear and Worm.

-` References Ctedin the le of this patent UNITED STATES PATENTS Cirrito-et al. a June 14, 1955 

